7 research outputs found
Non-perturbative saddle point for the effective action of disordered and interacting electrons in 2D
We find a non-perturbative saddle-point solution for the non-linear sigma
model proposed by Finkelstein for interacting and disordered electronic
systems. Spin rotation symmetry, present in the original saddle point solution,
is spontaneously broken at one-loop, as in the Coleman-Weinberg mechanism. The
new solution is singular in both the disorder and triplet interaction
strengths, and it also explicitly demonstrates that a non-trivial ferromagnetic
state appears in a theory where the disorder average is carried out from the
outset.Comment: 4 pages, 1 figur
Metal-Insulator Transition of Disordered Interacting Electrons
We calculate the corrections to the conductivity and compressibility of a
disordered metal when the mean free path is smaller than the screening length.
Such a condition is shown to be realized for low densities and large disorder.
Analysis of the stability of the metallic state reveals a transition to the
insulating state in two-dimensions.Comment: 11 pages, REVTEX, 1 figure included; Final versio
Conducting phase in the two-dimensional disordered Hubbard model
We study the temperature-dependent conductivity and spin
susceptibility of the two-dimensional disordered Hubbard model.
Calculations of the current-current correlation function using the Determinant
Quantum Monte Carlo method show that repulsion between electrons can
significantly enhance the conductivity, and at low temperatures change the sign
of from positive (insulating behavior) to negative (conducting
behavior). This result suggests the possibility of a metallic phase, and
consequently a metal-insulator transition,in a two-dimensional microscopic
model containing both interactions and disorder. The metallic phase is a
non-Fermi liquid with local moments as deduced from a Curie-like temperature
dependence of .Comment: 4 pages; 4 postscript figures; added (1) a new figure showing
temperature dependence of spin susceptibility; (2) more references. accepted
for publication in Phys. Rev. Let
Schwinger-Keldysh Approach to Disordered and Interacting Electron Systems: Derivation of Finkelstein's Renormalization Group Equations
We develop a dynamical approach based on the Schwinger-Keldysh formalism to
derive a field-theoretic description of disordered and interacting electron
systems. We calculate within this formalism the perturbative RG equations for
interacting electrons expanded around a diffusive Fermi liquid fixed point, as
obtained originally by Finkelstein using replicas. The major simplifying
feature of this approach, as compared to Finkelstein's is that instead of replicas, we only need to consider N=2 species. We compare the dynamical
Schwinger-Keldysh approach and the replica methods, and we present a simple and
pedagogical RG procedure to obtain Finkelstein's RG equations.Comment: 22 pages, 14 figure